Furnace



Patented June l1, 1929.

UNITED STATESA PATENT OFFICE# LUIS DE FLOREZ, F POMFRET; CONNECTICUT,ASSIGNOR T0 THE TEXAS COMPANY,

lA CORPORATION OF DELAWARE.

- rUaNAcE.

Application led July .2,

to avoid the injurious 'effects of local overjA 1o heating, and severalmeans for obtaining this result have been proposed. So far as I amaware, however, none of the proposed methods result in a complete orsubstantially complete separation, and'recourse is had to suchexpedients as. shielding the tubes by a refractory substance or the likein order .to avoid t-he effects ofheat transfer by convection.

In the apparatus'ofmy invention I secure 1926. Serial No. 120,067.

of the flowing current of-the products of combustion. Furthermore, thesection 0f the passaget-hrough which the products of combustlon flow ismaintained substantially constant which tends to avoid turbulences inflow which might throw the hot gases against the tubes. The gases,having radiated heat to the vertical elements and consequently beenreduced in temperature, then pass into the economizer section at such atemperature as vto be substantially nonradiant. The hot gases here comein contact with and flow around a second group of heatabsorbing tubeswhich are thus consequently adapted ,Ito absorb the convectioncomponentof the leat.

'A feature of the invention is the annular arrangement of heat absorbingtubes Within the combustion chamber permittingI the flama substantiallycomplete -separation of -thm ing gases to pass vertically through theanradiant and convection heat without resort to the interposition ofrefractory' shields or the like between the source of heat and thetubes, the source of heat and the tubes being v at all times in opencommunication; The nature of my apparatus furthermore, permits of anarrangement such that sagging of the tubes from lthe effects of heat isavoided, the tubes are readily removable for cleaning and the structureof the furnace is greatly cheapcned and simplified.

' The preferred embodiment of my invention consists of a furnace havintwo sections, a combustion chamber of su stantially uniform crosssection provided with tubes to absorb the. heatof radiation only, and aneconomizer section where the products'ofcombustion come into directcontact with a bank of heating elements placed in their ath. Ipreferably construct my combustion c amb er in cylindrical form,disposing the tubes vertically and supporting them from an upper tubesheet and arranging them so that they virtually line the inner surfaceof the bustion ass vertically through the center of the comgustionchamber in a direction generally parallel to the plane of the tubes,radiating heat to be vertically disposed tubes but not transferring anysubstantial amount of heat thereto by contact since the bulk,of thegases will not come in contact with them and the atipsphereimmediately'surrounding the tubes is substantially out combustion chamber. Theproducts of com-v avoiding the necessity of shielding the tubes asheretofore practiced, such as, for instance, imbedding them in the walland roof of the combustion chamber, or incasing them in heat resistingmaterial. l

When the vertically disposed tubes arealranged circularly about thesource of heat and the path of the heated gases they form aprotective'lining or shield for the 'walls of the furnace, whichconsequently may be of lighter construction, and less heat will be lostby radiation through the walls, as they receive only a portion of theheat imparted to them in existing furnace designs.

y The invention also provides other novel arrangements, such as a simplemethod of supporting the tubes, whereby they may 'be readil removed .forrenewal and accessible from oth ends for cleaning.

"The invention will best be understood if thefollowing description isread in connection with the accompanying drawings, vin which A Figure-1- is' a side elevation partially in section of a furnace according tomy inven- Y 'scale of the upper tube'N sheet of the combustion chambershownin Figure 1;

Figure 3 is a detail-view showing themani n'er of mounting the tubes inthe combustion chamber as shown in Figure 1;

Figure 4 is a detail perspective view of the lower casting giving accessto the bottom of the tubes of the combustion chamber of Figure 1;

Figure 5 is a central longitudinal section through a modified form of myinvention in which the combustion chamber is fired from the top, theproducts of combustion descending and passing through an undergroundflue into the economizer section;

Figure 6 is a detail view showing the manner of mounting the U-tubesused in the combustion chamber shown in Figure 5;

Figure 7 is a section on the line 7-7 of Figure 5, showing the manner inwhich the tube ends are connected; and

Figure 8 is a detail plan view of the upper tube sheet of the combustionchamber shown in Figure 5.

In the embodiment of my invention shown inFigures'l to 4, 10 representsa cylindrical combustion chamber built of brick work or other suitablematerial which 'may be held in shape merely by the circular bands 11. Itwill be understood that the combustion chamber may equally well be madesomewhat conical or chimney-like in shape, and that this constructionmay be desirable with a high furnace as an aid to structural stabilityor for the purpose of modifying the section to allow for the change involume of the products of combustion to maintain uniformity of low. Atthe bottornof the combustion cham ber a burner 1 2 or other source ofheat is located inside the tire box 13, the sides of which extend wellabove the burner. At the top of the combustion chamber and extendingdown into the chamber is aiiue or passageway 14 connecting thecombustion chamber. with the economizer section 15, in which is locateda bank of tubes 16 preferably positioned horizontally at right angles tothe path of the heated gases therethrough. Circularly arranged withinthe combustion chamber 10 adjacent the side wall but not in contacttherewith are the vertically disposed tubes 17 supported from an u pertube sheet 18. The tubes so arranged orm a surface virtually lining theside wall of thefurnace and shielding it from the intense heat to whichcombustion chamber walls are ordinarily subjected. As shown in Figure 1,the tubes 17 extend well above the lower end of the flue 14 and belowthe top of the fire box 13. The hot products of combustion flowing upfrom the burner 12 pass through the center of the furnace, radiatingheat to the annularly arranged tubes 17 but not transfertures 19 in thetube sheet 18 and the lower ends project into an annular casting 20extending around the firebox, which holds the tubes in place and spacesthem evenly in relation to one another. The casting 20 serves thefunction of a lower tube sheet, and is preferably formed in a pluralityof arcuate sections open along their outer wall, as shown in Figure 4.Each section may be provided near each end with a strut 21, placed insuch position that it will not interfere with the access to the tubeheaders. The tubes pass through apertures in the upper surface of thecast-ing 20 into the chamber thus provided. The tubes are connectedtogether in series by headers 22 located at their -ends as shown inFigure 3. Ready access may be had to either end of the tubes by means ofplugs 23 in the headers 22 for cleaning or otherwise.

As is usual in heating apparatus of this type, the oil or other liquidto be heated Hows first through ythe tubes 16 of the economizer section15 and then through the tubes 17 of the combustion chamber l0.Preferably the oilin the economizerl section flows countercurrent to theflow of the products of combastion, enteringl the lowest tube 16` ofvthe economizer section and fiowing upwardly through the tubes 16connected in series, the final tube 16 being connected to the upper endof one of the tubes 17 in the combustion chamber 10. The alternate endsof the tubes 17 are connected by headers as shown in Figure and that theupper end of the fire box 13 exy tends above the lower casting 20,forming shoulders behind which gas pockets are formed, thereby tendingto prevent the entrance of the fiame into these corners and consequenterosion of the tubes at these points. These shoulders also serve tokeepl the flame somewhat centered and away from the tubes during itsvertical travel.`

It will be seen that the ends of the tubes and the headersconnecting-them are protected from the flame by being housed outside ofthe heating zone.

In the embodiment of my invention shown in 'Figure 5, which will bedescribed only in so far as it differs from that shown in Figure 1,the'combustion chamber 25 is fired fromthe top by a burner 26. In thismodification the connecting flue 27 is located below the combustionchamber 25 and the economizer ring any substantial amount 'of h'eat tothe'n 28, and it is possible to support the tubes in tubes by contactsince the tubes are situated out of the path of the gases.

The tops of the tubes extend through aperthe combustion chamber in sucha manner that when in need of cleaning, a tu' e may be readily removedand a clean tube substituted, thus v to accommodate the ends of the tube30. The

U-tubes are connected together by return bends 34 which are joined tothe tubes by unions 35. In this manner the tubes are held in place onlyby their own weight and are free to expand or contract as they Varyintemperaturc.

A furnace constructed in accordance with my invention eifectuallydistributes the work done by the heating surfaces and to a large extentreduces the possibility of overheating of elements' which would bedetrimental either to the surfaces thus attacked or to the fluid beingheated and flowing within the tubes. As will be seen, this isaccomplished by absorbing heat by radiation from the flame until theproducts of combustion have been so reduced in temperature that they canbe safclyput into contact with the usual form of heat-ing elements.

It is, of course, desirable to burnv fuel with the least4 amount ofexcess air possible, which always results in a high fire box temperaturewhich is detrimental to the walls of the combustion chamber and to thefirst elements with which the products of combustion come into contact.

By absorbing the radiantiheat from the intense flame caused by burningfuelunder proper conditions, `the temperature of the products ofcombustion passing out of the combustion chamber is reduced eilicientlyby transferring the portion lof the heat that can be withdrawn byradiation and making it perform useful work. The transfer rate on thefirst contact elements is thus reduced to a safe limit, at the same timepermitting efficient combustion of the fuelv without the necessity ofadmitting excess air.

By disposing the tubes vertically, it will be noted that the section atright angles to the path of the hot gases is substantially uniform,tending to permit a smooth flow and to avoid the forming of eddiesaround the tubes which would cause a transfer of heat by contact. If thetubes were disposed ging of the tubes, but is an important factor ineliminating heattransfer by contact on the radiant heat elements.

The circular form of the combustion chamber and the shielding of thewall by the heat elements reduces the lcosts of constrction by utilizinga stable form of structure and permitting the use of lighter walls.

The steel work required to hold the combustion chamber together islargely reduced over furnaces of .rectangular sections and the necessityof using arches and roof sections is avoided.

It will be obvious that changes can be made in the design and that thecombustion chamber can be built rectangular in cross section withoutdeparting from my invention, although the combustion chamber ispreferably made circular in form for the above reasons and this circularform is distinctly an improvement on the existing practice. y

In the invention shown by the drawings, one row of tubes has beenindicated in the combustion chamber. This, however, is primarily for thepurpose of illustration and I contemplate, when necessary, using two ormore rows, preferably in staggered relationship, which may be desirableto absorb as much of the radiant heat as possible, and furthermore, thecombustion chamber and the economizer sections may be constructed oneabove the other if desired, although the indicated arrangement ispreferred for structural reasons.

Where the term substantially cylindrical combustion chamber is used inthe claims,l

it is intended to include a chimney-like construction with somewhatsloping sides.

While two embodimentsof my invention have been described in detail inthevforegoing specification for the purpose of fully disclosing myinvention, it is to be understood that my invention is not limitedthereto, but includes all changes and modifications whcih fall within,the scope of the appended claims.

What I claim is:

1'. In afurnace, a vertically arranged substantially c lindricalcombustion chamber, a plurality o vertically disposed heat absorbingtubes annularly arranged therein ad]a cent to the walls of thecombustion chamber, means for directing burning fluid fuel and theproducts of combustion thereof in a, central, longitudinal andunobstructed path through said chamber and substantially out 'of contactwith said tubes, and means for removably suspending said tubes fromtheir upper ends whereby the lower portions thereof may be capable oflateral movement.

2. In a furnace, a vertical combustion chamber, a burner chamber locatedat one end of said combustion chamber, an outlet ue located at the otherend thereof, said burner chamber and said outlet ueextending into saidcombustion chamber and having crosssectional areas less than thecross-sectional area of said combustion chamber, and a continuousheating coil arranged in a series of vertically disposed interconnectedtubes about said combustion chamber adjacent the Walls thereof andoutside the path of the products of combustion, to enable the passage ofa continuous Stream of heat absorbing fluid serially through said tubes.

3. In a furnace, a vertical combustion` chamber', a burner chamberlocated at the upper end thereof, an outlet flue located at the lowerend thereof, said burner chamber and said outlet flue extending intosaid combustidn chamber substantially centrally thereof and havingcross-sectional areas less than the cross-sectional area of saidcombustion chamber, and a continuous heating coil arranged in a seriesof vertically disposed interconnectedu U-shaped heat absorbing tubesabout said combustion chamber adjacent the Wall thereof and outside thepath of the products of combustion, to enable the passage of acontinuous stream of heat absorbing fluid serially through said tubes.

4. In a furnace, a vertically arranged substantially cylindricalcombustion chamber, a continuous heating coil composed of a series ofvertically disposed interconnected heat absorbing tubes adjacent to thewall of the combustion chamber and disposed on an annular pitch circlethe center of which substantially corresponds With the center of thecombustion chamber, and means for` directing burning fuel and theproducts of combus- .tion thereof in a central longitudinal andunobstructed path through said chamber l`and substantially out ofcontact with said tubes.

5. In a furnace, a vertically arranged substantially cylindricalcombustion chamber,

means for passing products of combustion heated to a radiatingtemperature centrally and longitudinally thereof in an unobstructedpath, and means in said combustion cham'- ber for cooling the productsof combustion to a substantially non-radiating temperature comprising acontinuous heating coil composed of a series-of interconnectedunshielded heat absorbing tubes positioned vertically in the chamber andoutside the direct path of the hot products of combustion and arrangedin substantially 'uniform spaced relationship to each other and to thechamber Wall, enabling the passage of a continuous stream of heatabsorbing fluid serially through said tubes, whereby local overheatingof Walls aud tubes is avoided and absorption of heat by radiation ismaintained substantially uniform among the tubes.

(i. In a furnace, a substantially cylindrical vertical combustion`chamber, a continuous heating coil composed of a series of verticallydisposed interconnected heat absorbing tubes adjacent to the Wall of thecombustion chamber and disposed on an vannular pitch circle the centerof which substantiallycorresponds with the center of the combustionchamber, a burner located at one end of the chamber, so positionedcentrally with respect to said tubes as to impel its iame and theproducts of combustion in an unobstructed vertical path substantiallyparallel to and out of direct contact with said tubes, and means forleading away the combustion gases from the opposite end of said chamber.

In testimony whereof, I have signed my name to this specification this30th day of June, 1926.

LUIS DE FLOREZ.

